1. Field of the Invention
The invention relates to a system for guiding projectiles to a target. More particularly, the invention relates to a system for the long range guidance of projectiles to a target without the complexity of fully guided munitions.
2. Description of the Related Art
The effectiveness of gun launched projectiles is directly related to the accuracy with which they can be delivered to the target. Over the years, numerous advancements have been made to gun systems that have greatly improved the accuracy with which projectiles can be delivered to the target. Among these advancements are aerodynamically stable projectiles, guns with longer barrels, improved barrel straightness, tighter tolerances on gun-projectile interface, higher muzzle velocities, and improved sighting and fire control systems. Although these efforts have significantly improved targeting accuracy, there is constant need in the military for increased effectiveness in delivery accuracy. This need and desire for high delivery accuracy led to the development of fully guided munitions. Fully guided munitions utilize various seekers coupled to some type of trajectory divert system (control fins, thrusters) through a closed loop control system to continuously track and maneuver toward the target.
Two categories of guided munitions systems are generally known in the art, autonomous and command guided weapons. Autonomous guided weapons generally contain control thrusters, attitude sensors, optical and/or radar based target sensors, hardware and software to accomplish target tracking, and projectile control processors for making guidance computations. Such known autonomous guided weapons include The Maverick, Stinger and Advanced Medium Range Air-To-Air Missile (AMRAAM).
Known command guided systems involve more control by an operator than automated systems. These systems generally use optical sensors or radar to image targets toward which an operator will lead the weapon. Weapons of this type, such as a Tube-launched Optically tracked, Wire guided (TOW) missile, typically carry an attitude reference gyro to define body roll position and an aerodynamic tail control system. Further, U.S. Patriot missiles are known to use attitude reference systems to cause commanded maneuvers to occur in the commanded direction. Further description of automated and command guided weapons systems can be found, for example, in U.S. Pat. No. 5,685,504.
While fully guided projectiles such as these offer the possibility of pinpoint accuracy at extended ranges they suffer from a number of disadvantages relative to unguided projectiles. Maneuvering all the way to the target requires large divert capability which leads to large interior volume requirements. Large rounds tend to have low muzzle velocity and high drag which, may lead to a need for an on board propulsion system in order to achieve acceptable terminal ballistic performance. Also, complex navigation systems employing autopilots and inertial measurement units may be needed. All of these systems tend to be costly and have survivability issues in the high acceleration gun launch environment. Fully guided projectiles are also difficult to develop and tend to be very costly relative to unguided ammunition. Accordingly, it is desirable to have projectiles with improved accuracy relative to unguided rounds without the complexity of a fully guided projectile. The present invention provides a solution to this need.
The present invention provides a system for the long range guidance of projectiles to a target utilizing a photo detector array and an arrangement of single use thrusters. The system is used to make small trajectory corrections at long ranges from targets such that only minimal maneuvering is required. This allows for minimizing of the size of the guidance system components and an overall reduction of the projectile size as compared to fully guided munitions.
The invention provides a guided projectile comprising:
a) a long rod penetrator body having a front end and a back end;
b) a detachable nose cone attached to the front end of the body;
c) a lens positioned within and at the front end of the body behind the nose cone;
d) a photo detector array positioned within and at the front end of the body behind the lens, said photo detector array comprising a plurality of circumferential and radial sectors and a central inactive region, said circumferential and radial sectors intersecting one another to form a grid around the central inactive region, the grid comprising a plurality of light sensitive grid regions;
e) a microprocessor positioned within the body and electrically connected to the photo detector array; and
f) a thruster array coupled with the body, positioned to impart a thrust away from the body, and electrically connected to the microprocessor.
The invention also provides a process for guiding projectiles comprising:
A) firing a projectile toward a target, said projectile comprising:
i) a long rod penetrator body having a front end and a back end;
ii) a detachable nose cone attached to the front end of the body;
iii) a lens positioned within and at the front end of the body behind the nose cone;
iv) a photo detector array positioned within and at the front end of the body behind the lens, said photo detector array comprising a plurality of circumferential and radial sectors and a central inactive region, said circumferential and radial sectors intersecting one another to form a grid around the central inactive region, the grid comprising a plurality of light sensitive grid regions;
v) a microprocessor positioned within the body and electrically connected to the photo detector array; and
vi) a thruster array coupled with the body at an outsider surface thereof, and electrically connected to the microprocessor, each thruster being positioned to impart a thrust away from the body;
B) removing the nose cone from the body, revealing the photo detector array;
C) aiming a laser at a target, said laser being reflected from the target toward the lens, the lens projecting an image from the laser onto at least one light sensitive grid region of the photo detector array; and
D) transmitting a signal from said at least one light sensitive grid region to the microprocessor corresponding to the grid region; and optionally
E) firing said thrusters in a sequence determined by said microprocessor which is sufficient to guide the projectile to the target.